Transillumination is the technique of sample illumination by transmission of light through the sample. Transillumination is used in a variety of methods of imaging.

Microscopy

In microscopy transillumination refers to the illumination of a sample by transmitted light. In its most basic form it generates a bright field

Bright field

Bright field may refer to:*MV Bright Field*Bright field microscopy...

 image, and is commonly used with histological stains. More advanced transillumination techniques include phase contrast and differential interference contrast microscopy.

Medicine

In medicine transillumination generally refers to the transmission of light through tissues of the body. A common example is the transmission of light through fingers, producing a red glow due to red blood cells absorbing other wavelengths of light. Organs analysed include the include the sinuses, the breasts and the testes. It is widely used by pediatricians to shine light in bodies of infants and observe the amount of scattered light. Since their skeleton is not fully calcified, light can easily penetrate tissues. In 2008 a new product the Breastlight was launched which works on the principle of Breast Transillumination. Although it does not appear to be as accurate as Mammography and Biopsy in the diagnosis of breast cancers it has found a useful application as an aid to Breast Awareness and Breast Self Examination as a low cost non-diagnostic device. Common examples of diagnostic applications are:

Hydrocephalus (water head)

Light penetrates to the inside of the skull of the infant. If there is an excess of cerebrospinal fluid

Cerebrospinal fluid

Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...

 (CSF), light is scattered to different parts of the skull, producing patterns characteristic to hydrocephalus. The device used in this operation is a Chun gun that uses a 150 watt projection bulb as a light source.

Pneumothorax (collapsed lungs)

Bright light penetrates the thin front chest wall and reflects off the back chest wall to indicate the degree of pneumothorax. To treat it, a physician inserts a needle attached to a syringe into the area of collapse to remove the air between lungs and chest wall, causing the lung to reinflate.

Dentistry

Bright transilluminated light can highlight dental caries

Dental caries

Dental caries, also known as tooth decay or a cavity, is an irreversible infection usually bacterial in origin that causes demineralization of the hard tissues and destruction of the organic matter of the tooth, usually by production of acid by hydrolysis of the food debris accumulated on the...

 and sign of dental trauma

Dental trauma

Dental trauma refers to trauma to the face, mouth, and especially the teeth lips and periodontium. The study of dental trauma is called dental traumatology.- Types :* Tooth fractures**Enamel infraction**Enamel fracture**Enamel-dentine fracture...

 such as enamel infractions.